engleski

ABA to Enhance Stress Tolerance of Vegetable Transplants

High air temperatures with dry winds and rapid soil drying conditions encountered in many southern regions of the U.S. can greatly reduce stand establishment of vegetable transplants. Understanding the morphological and physiological characteristics that moderate transplant shock can provide a basis for elucidating the complex mechanisms underlying transplant stress tolerance. The ability of transplants to tolerate transplant shock and resume growth is often determined by balance between root water uptake and leaf transpiration, and is linked to shoot/root growth. The development of antitranspirant compounds aimed to reduce transpiration and/or improve plant growth has broadened opportunities for research in vegetable species. We investigated the influence of physiological compounds [abscisic acid (ABA) and aminoethoxyvinylglycine (AVG)] and physical (‘ AntiStress’ , ‘ Transfilm’ , and ‘ Vapor Gard’ ) antitranspirants on the growth and physiology of pepper and artichoke seedlings exposed to one or two cycles of desiccation. In pepper, root application of ABA enhanced desiccation tolerance compared to foliar application. Leaf photosynthesis and conductance decreased upon ABA foliar application (up to 2000 mg L-1) ; however, photosynthesis rates recovered within a few days of application. Throughout two cycles of desiccation on pepper seedlings, ABA had a stronger effect in reducing stomatal conductance and photosynthesis while increasing leaf and stem water potential compared to AVG or physical antitranspirants. Most transplant growth changes occurred at the shoot level, and the control of shoot growth by ABA appeared to be transient. Similar trends were measured for artichoke seedlings following foliar ABA (1000 mg L-1) treatments. Our results suggest that exogenous ABA is effective to modulate shoot growth, enhance stress tolerance and ultimately improve field establishment of pepper and artichoke transplants.

abscisic acid; antitranspirants; pepper; photosynthesis; stand establishment; stomatal conductance; tomato

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